This invention generally relates to ion implantation. More particularly, it relates to apparatus for accurately measuring the dose implanted into targets. Even more particularly, it relates to an improved apparatus for activating, measuring, and controlling the dose implanted.
Ion implant dose is presently controlled by counting ions with an electrical counter, such as a Faraday cup, which is correlated to sheet resistance, spreading resistance, or SIMS measurements made on monitor wafers. Monitor wafers are run periodically to verify the calibration and to measure implant tool consistency. These monitor wafers are annealed along with product wafers after the implant process is complete. Sheet resistance and other measurements are then made on the monitor wafers. However, the correlation between ion count and dose has not been adequate since some ions are neutralized during their flight and some ions bounce out of the cup and therefore are not detected by a Faraday cup. Furthermore, the correlation measurement with the monitor wafers is accomplished well after product wafers from that batch have completed ion implant processing. Thus, a better solution for ion implant measurement is needed that is more accurate and that eliminates delay between implant and measurement.
It is therefore an object of the present invention to improve the in-situ measurement of dose.
It is a further object of the present invention to provide a way to activate the dose implanted in a substrate while the substrate is still in the ion implant tool.
It is a further object of the present invention to provide a way to measure the dose implanted in a substrate while the substrate is still in the ion implant tool and while corrections to the implant can still be accomplished.
It is a feature of the present invention that the substrate is implanted with a dose of a dopant and the substrate is then annealed within the vacuum system of the implant tool.
It is a further feature of the present invention that the substrate is implanted with a dose of a dopant, annealed to activate the dopant, and then the annealed implant is measured, all within the vacuum system of the implant tool.
It is an advantage of the present invention that tighter control of implant dose is provided.
These and other objects of the invention are accomplished by a method of processing a semiconductor substrate comprising the steps of implanting the substrate with a dose of a dopant in a vacuum system and activating said dopant while said substrate is within said vacuum system. The dose can then be measured within the vacuum system.
Another aspect of the invention is an ion implant system, comprising a vacuum chamber comprising an ion implanter for implanting a semiconductor substrate ith a dopant, said vacuum chamber further comprising an annealer for activating said dopant. The vacuum chamber can also have a measuring system for measuring a parameter related to the dose of dopant implanted. A semiconductor substrate can be implanted, annealed, and measured while remaining in the vacuum system.